About 80% of hospital patients in the United States require IV therapy and 50% of IV lines fail due to infiltration, a clot in the cannula, an inflammatory response of the vein, or separation of the cannula from the vein. IV infiltration is usually accompanied by pain, erythema, and swelling at the cannula tip or the insertion site. Severe infiltration may lead to necrosis requiring skin debridement, skin grafting, or amputation. Early detection of infiltration prevents the occurrence of serious incidents that may require surgical correction. The long-term objective of this project is to develop an infiltration sensor for monitoring IV failures. The Phase II research design includes the development of an advanced prototype, improvement of algorithms, evaluation of the prototype on animal models and human measurements, investigation of its accuracy and utility, and the examination of the commercial potential. The innovation of this project lies in the use of an optical method coupled with the advanced development in fiber optics and algorithms for tissue optics to provide a means for noninvasive monitoring of the IV sites. It will provide routine, automated, continuous, and real-time monitoring capabilities for patients undergoing IV therapy.